Radio transmission receiving system



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RADIO TRANSIISSION RECEIVING SYSTBI Filed A s- 29. 1921 2 Sheets-Sheet 2 RADIO FIE ENCY as LLATOR #IIHW J I 11 a; 8 6 f? RAD O 4 '5" -l anvento'c U gum (mam his fl-btom q 2 2 Patented Aug. 28, 1928.

UNITED STATES HENRI CHIREIX, OF PARIS, FRANCE.

RADIO TRANSMISSION RECEIVING SYSTEM.

Application filed August 29, 1921, Serial No. 496,666, and in France January 16, 1920.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

This invention relates to simultaneously transmitting and receiving messages of the human voice. The invention is equally well adapted for use in radio electric systems and to systems in which communications are established through metallic lines. The 1nvention does not require the use of more than one antenna at each station (or more than one line between two stations) and does not necessitate the use of a particular frequency in each direction of the communication. In accordance with the invention, I eliminate the potential difference due to the sending which exists between two given points of the member that makes possible the communication (antenna or line) in such a manner that, at all times only the potential difference due to the receiving is manifested between these two points. These two points may therefore be connected m with the receiving ap aratus, the operation of which will be affecte only by the signals coming from a distance and not those that originate locally.

My invention is illustrated in the accompanying drawings in which Figure 1 shows diagrammatically one arran gement according to my invention;

Figure 2 shows a modification thereof Figure? shows an arrangement in which a plurality of vacuum tubes are used to supply the antenna current and also the neutralizing current;

Figure 4 represents an arrangement similar to Figure 3 except that an additional neutralizing arrangement is provided, and;

Figure 5 represents an arrangement wherein neutralization of the transmitting current in the receiver is effected in the receiving circuit only.

Attention is now directed to Fig. 1, wherein a system is illustrated in which radiotelegraphic waves are transmitted. The potential difference existing between two points 1 and 2 of an antenna supplied with current through the primary winding of a radiotransformer 3 connected with a high frequency current source, is eliminated by means of a second transformer 4 connected to another source, the electromotive force of which has the same frequency and is suitably derived from and based to the E. M. F. of the said source. ssuming that this second source has some influence on the sending, its

action may be eliminated if it is necessary that the useful transmission energy be introduced exclusively through the transformer 3. Fig. 2 shows a circuit arrangement in which this last mentioned compensation is taken into consideration. In this figure, 1 and 2 are the points of the antenna between which the potential difference due to the operation of the sending source supplying current to the antcnna through transformer 3 is eliminated. i is the transformer through the agency of which this eliminating effect is obtained. As above stated, this transformer is connected with a current source of the same frequency as the sending current source and the electromotive force of which presents a suitable phase relation. Furthermore, the effect that this transformer coil 4 has on the sending is compensated by means of a coil 4.

To illustrate further and not to limit the invention, an embodiment is shown in Fig. 3 in which three-electrode tubes are used. As shown therein the high frequency energy is delivered by atube (or group of tubes) schematically illustrated at 6, which supplies current to the antenna through the transformer 3. This tube (or group of'tubes) is driven independently by an oscillator diagrannnatically sh wn. A second tube (or group of tubes) 7 annuls by means of the radiotransformer at the potential difference that might exist between the points 1 and 2 due to the current supplied through the trans former 3. The power supplied by each group of tubes is regulated by adjusting the heating rhcostats. This may be also accomplished by varying the number of cells in the plate battery.

The current supplied to the transformer 4 may be de-phased so as to balance the E. M. F.s on coil 4 by means of a condenser 9 having a variable capacity. This condenser may also be provided in parallel with the primary winding of the transformer 4 or, as shown, in series with the primary winding. Preferably, in the present case the plate of tube 7 is permanently connected with the current source 11, common to the various plate circuits, e. g. through a self inductance 10 having a high impedance. In the arrangement disclosed in the drawings, the grids are interconnected in such a manner that their potential follows the same variations. No arrangement is illustrated in which the grid circuits are coupled to the plate circuits to cause to generate oscillations. Any well-known arrangement may be used for this purpose (inductive, capacity, direct or intermediate circuit connection, etc.).

The object of the invention may be attained also by compensating the effect of the sending, by actuating the circuit traversedby the detected current instead of a portion of the antenna circuit. As shown in Figure 5 which is similar to Figure 4 described later except that compensating tube 7 and its associated circuits have been omitted. It is also possible to combine the two compensating methods and to neutralize the effect of the transmission partly on the antenna and partly on the circuit traversed by the detected currents. Such arrangement is schematically illustrated in Fi g. 1-,. The difference between Fig. 4 and Fig. 3 is that a tube 8 is added which detects a portion of the sending current. This detected current affects through the agency of transformer 11 the circuit of the detected currents supplied to the receiver 12. The phase of this current may be adjusted by means of a condenser 13.

Obviously, the invention is not limited to the above disclosed specific circuit arrangements and is generally applicable to installations in which the sending is accomplished by means of a high frequency oscillation genorator system adapted to supply two suitably depha'sed currents of the same frequency. Two high frequency alternators coupled to the same shaft may be used as shown in Fig. 1. The electromotive forces of these alternators should have the necessary phase displacement. Means have been disclosed for completely separating the functions of the two sources, onepr'oducin the useful energy for the sending and the ot ierthe compensating energy. However, this distinction is not always necessary. In the circuits of Figs. 3 and 4 which have no transformers corresponding to transformer 4 of Fig. '2, no such distinction has'been observed. In this case, the two generator groups do not have distinctly different functions, and'b'oth operate to produce useful energy and to efiect the'con'ipcnsating. A

The invention is readily applicable to'tlephony or telegraphy over wires by substituting lines in the place of the antenna.

Having described my invention, what I claim is:

1. In a radio system for simultaneous transmission and reception at the same frequency, the combination of a common unifilar transmitting and receiving antenna, a receiver tuned to the coimnon transmitting and receiving frequencyand coupled to a portion of said antenna, transmitting apparatus coupled to a second portion of said antenna in series with the first portion, means for detecting a portion of the trans mitter current, and means for introducing said detected portion of currcntinto said rccciver circuit in a manner to neutralise therein elfects due to transmitting current.

2. In a radio system for simultaneous transmission and reception at the same frequency, the combination of a commonuilifilar transmitting and receiving antenna, a receiver tuned to the common transmitting and receiving frequency, a transmitter comprising an oscillation generator, :1 receiving coil and a transmitting coil in said antenna to which the receiver and transmitter are respectively coupled, a circuit for coupling a. portion of the output of said transmitter-to said receiving coil, a detector circuit coil nected to said receiver, and a circuit arranged to rectify a portion of the output of the transmitter coupled to said receiver detectorycircuit to neutralize therein the effects of the transmitter current.

3. In a radio system for simultaneous transmission and reception at the same frequency, the combination of a common unifilar transmitting and receiving antenna, a receiver tuned to the common transmitting and receiving frequency, transmitter comprising an oscillation, generator, :1 receiving coil and a transmitting coil in said antenna to which the receiver and transmitter are respectively coupled, a detector circuit connected to said receiver, and a circuit arranged to rectify a portion of the output of the transmitter coupled to said receiver detector circuit to neutralize therein the efi'ects of the transmitter current.

, HENRI CHIRETX. 

